The human placenta functions as the interface between the mother and developing fetus. Proper function of the placenta is important for normal uncomplicated fetal development and maternal health. The placenta, like many tissues and organs, is subject to damage. Damage to tissues and organs can occur at the level of individual cells. The focus of this project is to determine the mechanisms by which trophoblasts repair injury to their plasma membranes. Trophoblasts are cells unique to the placenta and related structures. They have the capacity for cell division and self-renewal. They also have the ability to fuse and differentiate into the structure known as the syncytiotrophoblast (STB). The STB can be considered a giant cell with a very large number of nuclei that separates maternal blood from the remainder of the placenta. In addition, the STB is the site where gases and solutes (e.g., amino acids, ions, sugar, etc.) needed for fetal development first enters the placenta. Thus the STB is of critical importance. A unique feature of the STB is that it continuously sheds excess cellular material derived from fusing mononuclear trophoblasts called cytotrophoblasts. The structures containing this excess material that are shed are known as syncytial knots. The mechanism by which this shedding process occurs is not fully understood, nor is the mechanism by which the plasma membrane of the STB is repaired following shedding events. It is the goal of this project to determine the mechanism(s) used by trophoblasts to repair injury to their plasma membranes. Hypotheses have been developed that trophoblasts repair damaged membranes in a calcium-dependent manner relying upon specific proteins, including dysferlin and /or myoferlin to facilitate this process. The experimental approaches to testing the predictions of theses hypotheses incorporate methods of cell biology, biochemistry, and molecular biology.